*ctxabbr* is a Vim plugin to provide a convenient way to define a variant of
normal |abbreviations|, called as "context-sensitive abbreviations".
Normal abbreviations are short words which will be replaced with the words
they stand for whenever you enter the short words.
But sometimes, it is useful to replace such abbreviations
with some text according to the context - text around the cursor.

For example,

call ctxabbr#define('sc', 'System.Collections', '<using')

With the above setting, whenever you enter "sc", it is replaced with
"System.Collections" if it is entered after a word "using", or
"sc" otherwise. It is illustrated as follows: